The general goal of this proposal is to investigate the function of the gastrointestinal tract by measuring the production and absorption of gases in the gut. These general areas will be investigated. 1) The possible role of the colonic bacteria in alcohol-induced organ injury will be investigated. To this end, fecal samples will be collected from alcoholics and the volatile metabolites produced by the fecal bacteria during incubation with ethanol will be measured by gas chromatography. The production of these metabolites will be correlated with the presence of various forms of alcohol related disease. If a correlation is observed, this finding could help to explain the individual differences in susceptibility to the ranges of ethanol and help direct preventive measures. The influence of unstirred water layers in the gut will be assessed in vivo using a new technique which employs carbon monoxide (CO) as a probe. While this layer has been extensively studied in vitro, the lack of techniques to measure this layer in vivo has limited understanding of its physiological significance. The studies described will utilize CO absorption measurements to quantitate the thickness of the unstirred layer and assess its influence on the absorption rate of a variety of nutrients. A possible outgrowth of this study may be information which makes it possible to enhance or decrease absorption by manipulation of the unstirred layer. The production and consumption of H2 by colonic bacteria will be investigated. The novel aspect of this study is that H2 production and H2 consumption will be measured simultaneously whereas all previous studies of H2 "production" by fecal bacteria have measured net H2 production. The results of this study should elucidate some of the fundamental factors influencing the H2 breath test for carbohydrate malabsorption, identify the cause and direct therapy for flatulence, and enhance our understanding of the complex relationship between the fecal bacteria and the colonic environment.